1. Field of the Invention
This invention relates to a system and method for cultivating fish. More particularly, this invention relates to a system for cultivating fish that provides more control over the parameters of the fish cultivation process, increases the quantity of fish that may be raised per acre of water, and uses existing water sources, including some bodies of water wherein raising fish previously was not feasible.
2. Background Art
Fish is a major food source in the United States and the world. Raising the largest quantity fish at the least expense is necessary for an efficient operation. The efficiency of fish production may depend on the body of water being used. Not all bodies of water have been capable of effective production of fish. In many reservoirs, the amount of fish per acre has been limited by biological considerations; i.e., the waste produced by the fish increases the biological oxygen demand ("BOD") on the water, thus limiting the quantity of oxygen available to the fish.
Some floating fish pens are currently available to cultivate fish. For example, these floating pens are shown by Fast in U.S. Pat. No. 4,044,720 and by Fremont in U.S. Pat. No. 3,653,358 and U.S. Pat. No. 3,698,359. These fish cultivating devices do not remove fish waste or uneaten food from the water where the pen is floating. Instead, these waste products remain in the reservoir and increase the BOD. Thus, the fish cultivating systems available in the prior art do not allow an increase in the maximum quantity of fish that may be raised per acre of water because the systems provide no means to remove the oxygen-consuming waste and food products.
Additionally, although disease treatment is possible in existing systems, it is costly and time consuming. Once a problem is discovered in a cage cultivation system, the full body of water must be treated, not just the smaller cage holding the fish. The larger volume of water that must be treated correspondingly increases the treatment price and decreases efficiency. Alternatively, the cage must be encapsulated in plastic before treatment. With the floating pens, closely controlling the feeding and minimizing the waste is difficult, if not impossible. And, once the fish are ready to sell, the cost of retrieving the fish from several hundred feet netting and into the truck is expensive.
Furthermore, without aeration and water movement, the water of the reservoir may stratify. Stratification of water decreases the total amount of dissolved oxygen that the reservoir contains. As the amount of dissolved oxygen is reduced, the quantity of fish that a reservoir may support proportionally decreases. Existing fish cultivation systems do nothing to prevent or control stratification in the reservoirs in which they are used.